Carpenter&#39;s square.



J. BARKER. GARPENTBRS SQUARE. APPLICATION FILED AUG. 7, 1909.

Patented Mar. 15, 1910.

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JOHN BARKER, OF SAN FRANCISCO, CALIFORNIA.

CARPENTERS SQUARE.

To all whom it may concern:

Be it known that I, JOHN BARKER, a citizen of the United States, and aresident of the city and county of San Francisco, State of California,have invented new and useful Improvements in Carpenters Squares, ofwhich the following is a specification.

This invention relates to improvements made in a carpenters steel squareof that type or description in which the blades are arranged to foldtogether in order to bring the square into a smaller compass forcarrymg.

The object of the invention is to provide a oint of an improvedcharacter for uniting the blade and the arm of a folding steel square,that will hold the blade invariably at right angles to the arm andmaintain its true ')erpendicularity when the square is opened for use,and will have also such stiffness and rigidity when the parts are foldedthat they will not spring or bend out of line under the handling andrough usage to which a square of this kind ordinarily is exposed.

A ,further object of the invention is to provide a simple and effectivemeans or device on the square for locking or fastening the blades inposition at right angles to each other, and maintaining them rigidly inthat position while the square is in use.

These and other objects I attain in and by the peculiar and novelconstruction of parts and combination of parts constituting myinvention, as hereinafter fully described and pointed out in the claim.

Figure l of the drawings represents in side elevation the part of acarpenters steel square of my invention at the junction of the arm andthe blade, where those parts join each other at right angles, the bladebeing shown in full lines folded on the arm, and by the dotted lines asin the extended position. Fig. 2 is a similar view of the same parts inthe folded position looking at the opposite side of the square. Fig. 3is a similar side-view of the parts represented in Fig. 3 showing theblade opened and locked in position. Fig. 4 is an edge view of the twoparts of the joint separated but in relative position. Fig. 5 is a crosssection through the locking bolt when the blade and arm are locked atright angles.

The arm a which is usually longer and broader than the blade 6 in thesquare used by carpenters is provided with a tongue of Specification ofLetters Patent.

Application filed August 7, 190a.

Patented Mar. 15, 12bit). Serial No. 511,788.

the same width as the blade, but of reduced thickness, being formedintegral with the arm so as to constitute a lateral extension standinginvariably at right angles to the arm. This tongue is reduced inthickness from the outer end 2, which is cut on a diagonal line, back toa similar line 3 extending diagonally from the corner or inner angle atacross the arm to a point 5 on the outer edge of the square. The partincluded between these two lines 2 23, designated as the tongue (Z,corresponds with a similar tongue or part 6 formed on the blade Z) byreducing the thickness of the blade from the edge (3 back to the innerline 7 for the entire width; and the two parts cZc are fitted togetherto make a close joint when set one on the other with the blade at rightangles to the arm.

The pivot f uniting the blade to the arm is located outside the line 3at which the extension (Z joins the arm a, but as close to that line asit is practicable to place it and provide sufiicient metal surroundingthe pivot to secure the necessary strength in the joint. The position ofthe pivot is on a line that will bisect the angle included between theouter edge 2 and the inner edge 3 of the tongueindicated'at 1 Figs. 1, 2and 3so that having that point for its center, the blade can be turneddown or folded close to the arm; as the pivot is in such position withrelation to the two parts of the joint that the blade will liesubstantially parallel with the arm.

The outer edges 2-8 of the tongues are beveled and the inner edge 3 9where they join the portions of greater thickness are under cut, asshown, to let in the beveled edges when the blade and arm are set atright angles, with the effect to mutually interlock the two parts andsecure a stiff joint. A stiff and rigid joint is insured however by thelocking bolt of peculiar and novel construction consisting of aslidebolt 9 confined in a dovetailed slot 10 in the arm a, and fitting arecess 12 in the blade I), the latter being undercut or dovetailed alongthe edges to receive the bolt, which is correspondingly shaped on thesides and end to fit the recess.

The bolt 9 is provided with a screw-stop it the threaded end of whichbeing in line with a hole 13 in the recess 12 and a hole l-t in thetongue (Z on the arm serves to draw the parts of the joint tightlytogether and fix the blade invariably at right angles to the arm whenthe blade is opened and the bolt is set out from its slot into therecess.

A simple turn of the screw it after the bolt is set in line with thethreaded holes is suflieient to fix the blade accurately at right anglesto the arm. As thus constructed and arranged the parts of this jointhave the advantage of maintaining a true perpendicularity of the arm andthe blade which is always an important feature in a square of this kind,and of holding the blade invariably at right angles to the arm whileopened or adjusted for use.

The location of the pivot beyond the line of junction of the arm withthe blade but in relatively close relation to it permits the blade tolie substantially parallel with the arm and not at an angle thereto whenfolded, so that the liability of being sprung or bent or twisted at thejoint is very slight and is practically eliminated by this newconstruction of joint.

I claim r In a carpenters square having the blade adapted to told on thearm, the combination of an arm having a laterally extending tongue ofless thickness than the arm joining the arm on a diagonal line andhaving an oppositely inclined diagonal outer edge; a blade having atongue of corresponding thickness and of similar form to the tongue onthe arm, the said tongues being pivotally united and having theirpivotal points located outside the line of junction of the arm with itstongue and midway between the diagonal outer edge of the tongue and itsline of junction with the arm, and a locking means comprising the slidebolt on the arm, the recess in the blade and means on the bolt forlocking it in position when set into the recess in the blade.

JOHN BARKER. lVitnesses:

M. REGNER, E. E. OSBORN.

